how to make this happen?
trezor suite is not allowing to lock 1k, splits with next transaction
Research the wallet's ability to use coin control, my guess is probably no, but read the manual very closely and look for the term 'coin control' or 'inputs'. If still not possible and for example, you have 2001 Dash on the Trezor, create two new receiving addresses in your Trezor. Now create a transaction to send 1000 Dash to one address and another 1000 Dash to the other address in the one transaction. This should be possible in the wallet too, search on how to send to multiple recipients.
Also, search the forum for the 'perfect masternode guide' so you don't use the trezor for any other keys, because it is pointless and a massive pain in the ass.